Scratch - Uranus Explorer 2 {Scratch}

Scratch Uranus Explorer 2 Original Design / Scratch Built

Scratch - Uranus Explorer 2 {Scratch}

Contributed by Tom Markel

Construction Rating:
Flight Rating:
Overall Rating:

Published:	2011-08-14
Manufacturer:	Scratch
Style:	Ring/Tube/Cone Fin

Brief

Personal Challenge: A workin' model built from and themed on Toilet Paper Rolls, arrr, Rear Ejection (of course!) and fly-able with C engines

Components

8 High-Quality Toilet Paper Roll Centers*
BT 5
BT 20
Foam Board t' make Adapter Rings
Maskin' Tape (lots and lots o' Maskin' Tape)
Rubber Bands for Shock Cord
Standard 12 inch parachute

(*Regardin' "High Quality Toilet Paper Rolls," t' cores from t' industrial strength extra large rolls used in hospitals and office buildings by professional janitorial services are thicker, matey, me hearties, smoother, and tougher than t' stuff you get at t' grocery store. T' spirals are however very deep.)

Construction

Challenge: Build a rocket based on theme o' Uranus Explorer (but keep it PG rated)

At t' same time I be buildin' t' rocket (actually t' second rocket, matey, me bucko, t' Uranus Explorer 1 was a dismal failure) I be makin' up a story that went along with t' rocket. Well, blow me down! Blimey! I think t' best place t' put that is up front in this review, matey, so here it is.

INTERSPACE TELEX FROM SPACE COMMAND

URGENT: You have been ordered t' take IMMEDIATE command o' t' Uranus Explorer II.

BACKGROUND: In t' first half o' t' 21st century, arrr, matey, matey, concerns on Earth mounted regardin' global warming. Arrr! While thar be a great uproar about changin' human behavior t' combat this menace, arrr, ya bilge rat, t' problem solved itself in t' second half o' t' century. While t' well-meanin' efforts o' t' "Greens," as they came t' be called, matey, may have had some impact, matey, t' finite supplies o' fossil fuels expired by 2075. Ya scallywag! In addition, t' fight t' obesity epidemic, me hearties, t' fast grub enterprises were vilified by t' population. Ronald McDonald was hung in effigy in several countries. Avast! Since beef hamburgers were t' main stock in trade for these restaurants, shiver me timbers, arrr, t' demand for beef largely expired with t' fast grub franchises. Aye aye! T' final major source o' greenhouse gasses, t' cattle farms, also went t' way o' t' dinosaur. T' global warmin' scare was over.

T' loss o' cheap fuel and fast foods led t' a progressive sense o' dissatisfaction among t' people o' Earth, who attempted t' drown their sorrows in entertainment. Begad! Begad! Blimey! VCRs and DVD players gave way t' IPods, shiver me timbers, me bucko, Androids, me hearties, Playstations, Wiis, ya bilge rat, and other devices, all o' which shared two features. First, shiver me timbers, shiver me timbers, they required electricity. Second, they were a mindless waste o' time.

To replace t' fossil fuels, t' people o' Earth maximized their use o' renewable energy sources, me hearties, includin' Wind, ya bilge rat, Geothermal, arrr, matey, Hydroelectric, and Solar. T' first three were largely limited by geography. Solar, shiver me timbers, however, was only limited by surface area. Begad! By t' year 2125, matey, solar "farms" had sprung up over much o' t' Earth’s surface, arrr, includin' Antarctica, me hearties, and floatin' solar "mats" covered much o' t' oceans. Begad! Low Earth Orbit solar satellites created a virtual "traffic jam" in t' skies, t' t' chagrin o' terrestrial astronomers. Begad! Lookin' up at t' sky at night, arrr, more stars "moved" than remained in once place.

T' combination o' t' loss o' greenhouse gas generators and t' impact o' solar collectors shadin' much o' Earth’s surface as well as fillin' t' skies had an effect that should have been anticipated--- t' Earth's climate was headin' for a second Ice Age. Temperatures plummeted.

Many different plans t' restore t' greenhouse gas "blanket" were attempted. A nationwide chili marathon be probably t' most grandiose. It had little effect on t' global atmosphere, me bucko, me hearties, me bucko, but resulted in numerous hospitalizations throughout t' state o' Texas dues t' t' accumulation o' noxious gases. Ahoy! In desperation, me bucko, t' people o' Earth looked t' t' skies for help. Ahoy! Ya scallywag! T' United States, once an importer o' fossil fuels, matey, now developed a plan t' import greenhouse gases from space.

Of t' four planetary gas giants, shiver me timbers, t' highest concentrations o' methane are found around Uranus, arrr, at roughly 2% o' t' atmosphere by volume. Begad! Arrr! While further away than Saturn and Jupiter, ya bilge rat, manned expeditions t' Uranus in 2186 found t' planet had a rocky core with numerous central caverns. Avast! Begad! Concentrations o' methane within t' caverns approached 75%. Unlike Saturn and Jupiter, matey, t' caverns could be sealed, cleared o' t' methane, matey, heated, shiver me timbers, ya bilge rat, and pressurized. In other words, shiver me timbers, thar could be life inside Uranus.

Drillin' operations began in 2192, and t' planet be formally colonized under t' leadership o' Admiral Ezekiel Koli in 2199. T' fecundity o' E. Well, blow me down! Koli's descendents became legendary, and within 5 years t' colonists had spread throughout t' bowels o' t' planet. Begad! Methane gas generated within t' rocky core was diverted t' natural "vents" on t' planet surface. Avast! Aye aye! This gas be collected in Surface Repositories (dubbed "SuPositories.") T' SuPositories were then harvested by tanker ships and t' gas was transported t' Earth. T' effort has been thus far successful. Earth's temperatures have stabilized and are gradually returnin' t' 21st century levels. Begad! Ya scallywag! T' only casualty was t' state o' Utah, which seceded from t' Union when t' restoration o' "normal" temperatures forced them t' abandon plans for year-round skiing.

Durin' t' drillin' operations on Uranus, miners discovered rich deposits o' Amodium. Existin' in two chemical isomers, t' "L" or levo form and t' "D" or dextro form, Uranian Amodium be predominantly in t' D isomer. Arrr! Valued for its medical properties, Amodium-D is extremely useful in t' treatment o' dysentery. Earth's Amodium supplies were exhausted in t' early 21st century in a vain attempt t' stem t' tide o' large fecal outflows from Washington, D.C. Uranus produces 80% o' t' pharmaceutical grade Amodium-D in t' solar system. T' only other major supply o' Amodium-D is in t' asteroid belt. Arrr! Tanker ships, notorious for poor hygiene, were plagued with dysentery and t' production o' Amodium around Uranus rivaled t' methane minin' operations in profitability.

T' growin' population inside Uranus yearned for t' same amenities and distractions as their distant Earthly cousins. Ahoy! Blimey! Entrepreneurs, ya bilge rat, ever anxious t' make a credit, arrr, me hearties, established venues on t' Uranian satellites, includin' a Disney Theme Park, me bucko, ya bilge rat, "Part o' Your World," on t' satellite Ariel, me hearties, arrr, me bucko, a Lane Bryant Woman's Clothin' outlet store on t' satellite Titania, ya bilge rat, and a romantic bed and breakfast getaway, arrr, "A Quiver o' Love" on t' satellite Cupid. Ahoy! Begad! By 2250, Uranian commerce had established a respectable amount o' regularity.

Unfortunately, me bucko, t' hygienic habits o' t' Tanker ship crews did nay improve. Ahoy! Ahoy! Due t' failure in interspace decontamination procedures, one or more tankers have carried a type o' "animal fungus" from t' asteroids t' t' surface o' Uranus. These vile creatures reproduce rapidly and are incredibly adherent t' t' rock and ice surface o' t' Uranian core. Begad! They are particularly attracted t' t' relative heat around t' vents o' Uranus. Arrr! Dubbed, "Cling-Ons" by t' colonists, t' invaders have destroyed t' SuPositories and have multiplied t' t' extent that they are now obstructin' many o' t' methane outlets. Begad! Avast! T' buildup o' pressure behind t' vents is reachin' dangerous levels, producin' dyspepsia, nausea, and vomitin' among t' population o' t' planet. Begad! Minin' operations o' Amodium-D have ground t' a halt. Begad! Because thar be no local supply, an outbreak o' dysentery on t' satellite Oberon has required importation o' Amodium from t' asteroid belt. This has put an incredible load on an already strained interplanetary supply system.

T' situation is now CRITICAL.

We have deployed Remotely Operated Infrared Detectors (ROIDs) within all t' major vents t' monitor t' situation. Aye aye! Avast! T' ROIDs will detect focal temperature increases which herald obstruction. Aye aye! Additional SuPositories have been prepared t' replace those destroyed by t' Cling-Ons. Avast, me proud beauty! T' Jovian and Saturnine Fleets have been redirected t' assist in t' emergency.

T' initial scout ship, t' Uranus Explorer, was mothballed in 2195. Begad! Blimey! It has been recommissioned for t' rescue effort. Aye aye! Blimey! T' previous BVD-1 subspace engine has been upgraded t' t' BVD-2. T' ship has also been augmented by 4 Procto and Gamble Sharmin "Ultra" outboard engines t' give it interplanetary capability at 0.25 light speed.

Your mission is as follows:

Rendezvous with t' USS Colon Powell (commanded by Admiral Sigmoid Koli) and guide t' Fleets in t' evacuation o' Uranus.
Scour Uranus and wipe out t' Cling-Ons.
Monitor t' ROIDs. Arrr! At any hint o' sensitivity, insert t' replacement SuPositories t' relieve t' obstructed vents.
Restore Amodium-D minin' operations, me bucko, t' reduce t' frequency and urgency o' the runs betwixt t' asteroids and Uranus.

Addendum: On successful completion o' this mission, shiver me timbers, you and your spouse are authorized a 30 day furlough at t' "Quiver o' Love" on Cupid. Arrr! Begad! Remember, with 27 satellites, me hearties, thar be always a full moon around Uranus.

END TRANSMISSION

Back t' t' review. Well, blow me down! Avast! Goals o' t' rocket buildin' were as follows:

Had t' look at least slightly cool
Use Toilet Paper rolls for much or all o' construction
Rear End Ejection (naturally)
Inexpensive project
Standard (A, B, matey, or C) Engine size (see #4)
Write a background story.

After buildin' t' Estes Porta-Pot Shot, matey, and readin' notes from a reviewer who suggested a rear-ejection model, me hearties, started t' think o' other designs sort o' on t' same theme. Arrr! Original design became t' Uranus Explorer 1 (UE1), (which will be fairly similar t' t' UE2, me bucko, shiver me timbers, ya bilge rat, described here. Avast, me proud beauty! I found that usin' only two rolls for t' nose-cone fuselage combo resulted in a stubby rocket that I could nay get stable (I know, me bucko, I built it and tried. Aye aye! For some reason Tim Van Milligan doesn't have Toilet Paper tubes in t' RockSim inventory. Go figure!) So t' lengthen t' fuselage, had t' use two rolls connected (alternative would have been t' use a single paper towel roll, ya bilge rat, me hearties, but that would have violated t' theme. Well, blow me down! Would have had t' call it t' Brawny or t' Scrubber, me bucko, or somethin' else. Well, blow me down! But I digress...) You say, no problem, ya bilge rat, a coupler would work for this. Problem, since I pre-determined t' use aft end ejection, I needed a pristine smooth inner contour, matey, ya bilge rat, ya bilge rat, so a (standard) internal coupler wouldn't work. So I went with an external coupler. Well, blow me down! This o' course be aerodynamically suboptimal, arrr, me hearties, but since I wasn't plannin' t' set an altitude or duration records, ya bilge rat, me bucko, was acceptable. Begad! So I used an external coupler cut from another tube. I figured I would put t' launch lug in t' gap later (had I really thought it through, would have remember I could hide a launch lug in t' tube fins.) This still left a small step-off or "transition" on t' inside where t' two tubes butted together. Blimey! Avast, me proud beauty! I ran maskin' tape from end t' end along t' inside so that thar were no transitions t' trap or catch t' engine pod and recovery devices durin' aft ejection.

Next problem: t' nose cone. Begad! First, nay sure that toilet paper roll centers really come in a standard size for nose cones. Begad! Second, ya bilge rat, I'm cheap. Third, wanted t' keep overall weight o' t' body o' t' rocket light (more on this later.) 4rth, matey, wanted t' use as many TP rolls as possible. Blimey! Aye aye! Wondered---- how could I make a nose cone out o' a toilet paper roll?

By cuttin' 16 length-wise cuts nearly t' t' end o' t' roll, then cuttin' a diagonal out o' each section, matey, I be able t' create a roughly Ogive cone. Aye aye! Blimey! Aye aye! Blimey! Connected t' tips with tape. Avast! Blimey! Put a "shoulder" (again cut from another TP roll) on t' anterior end o' t' body tube. Attached this with CA t' t' previous two tubes I now have a fuselage (one-piece with t' nose cone) just under three TP rolls long I then ran strips o' maskin' tape LENGTHWISE from just beyond t' tip t' just aft/tailward o' t' nose-cone/fuselage joint). At t' tip, arrr, I cut the corners steeply and wrap around t' nose cone. Well, blow me down! I had t' run a few spiral wraps for support and t' maintain shape.

Nose Cone

Shoulder

Nose Cone/Fuselage

Finishing

As mentioned, t' buildin' and paintin' run together as t' paintin' was done before completely fittin' together t' parts.

Once I had t' shape roughed out, matey, arrr, it was time t' fill. Begad! Blimey! Ya scallywag! Blimey! However, I wanted t' have a clean paint job with different colors for t' fuselage and t' tube fins. Aye aye! Blimey! I felt that maskin' would be tough. But if I painted them first, me bucko, then I would be tryin' t' glue together painted surfaces. Begad! Blimey! That didn't sound like it would be t' strong. Ya scallywag! Blimey! Arrr! Blimey! On t' other hand, I KNEW exactly where all t' joints would be (I was usin' four tube fins, paired, arrr, arrr, on opposite sides o' t' fuselage. Well, blow me down! Blimey! Since 6 tubes would fit perfectly, matey, me hearties, I just placed marks at 60 degrees, matey, 120 degrees, shiver me timbers, matey, shiver me timbers, 240 degrees, and 300 degrees on t' fuselage. Ya scallywag! Blimey! On t' tube fins, two marks each, matey, 60 degrees apart, would suffice. Avast, arrr, me proud beauty! Blimey! For increased stability, I let 1/2 o' t' tube fins lag behind t' end o' t' fuselage (also thought would look cooler. Aye aye! Blimey! Later durin' actual preparation o' t' rocket for launch I found it did make access t' t' engine mount awkward.) So marked on all t' tubes where t' joints should be. Ahoy! Blimey! Well, ya bilge rat, blow me down! Blimey! I also marked where I wanted t' put t' launch lug.

I wanted t' "protect" t' joint areas from t' paint and sealer t' set up a stronger joint. Avast, me proud beauty! On t' UE1 I had placed thin strips o' maskin' tape over these areas. Blimey! Arrr! I discovered t' maskin' tape broke down under t' sandin' process, matey, so I tried Mylar tape strips, me bucko, me bucko, ya bilge rat, 1/4 inch wide. I placed a "tail" over t' edge/lip o' each tube, me hearties, and then wrapped t' very tip INSIDE t' tube. Avast, me proud beauty! Avast, me proud beauty! Turned out t' sandin' still wore off most o' t' tails, ya bilge rat, but t' tip piece wrapped inside was an adequate marker for removal o' t' tape later. Aye aye! Each strip was 1/2 t' length o' a single tube.

It took five coats/sandings o' Elmer's filler t' get a good smooth surface over t' nose-cone maskin' tape. Ya scallywag! Blimey! Therefore regardin' "savin' money" as a reason t' make your own nose cone--Unless your time is worth less than 25 cents an hour, you’re better off buyin' it from Tim. Arrr! But since this WAS a themed rocket, it seemed worth it. Avast! (Although me lovely wife wasn't happy about t' pile o' filler dust on t' front porch!) I need three coats/sandin' t' fill t' DEEP VALLEYS o' t' toilet paper roll spirals anyway, (another reason t' use REAL body tubes.) I sealed t' tube fins (outside only) t' same way.

Note that since this is a rear-ejection model, me bucko, it allowed me t' cover t' nose-cone/fuselage joint. While I be fillin' in t' maskin' tape defects and t' tube spirals, matey, it turns out I had enough filler t' cover t' external coupler. Ya scallywag! In fact, by t' time I be done t' slight residual "bulge" was hardly notice-able. Blimey! (Performance-minded rocketeers are probably shudderin' at t' added weight o' t' filler required t' accomplish THAT.)

When I was finished, I had a very nice fuselage with a smooth surface from tip t' tail, me hearties, me bucko, except for t' "break" in t' external coupler where I planned t' put t' launch lug. Well, blow me down! Blimey! Again, had I been thinking, me hearties, I would have filled this in too and put hidden t' lug in t' tube fin/fuselage joint. Aye aye! Blimey! I believe t' absence o' a nose-cone/fuselage transition gives t' rocket a retro Buck Rogers look. Arrr! Blimey! O' course, shiver me timbers, I also believe in t' tooth fairy. Well, blow me down! Blimey! Again, I digress......

I knew that tryin' t' fill in t' INSIDE spirals o' t' tube fins be goin' t' be hopeless. Avast, me proud beauty! I figured t' insides o' a spaceflight engine would probably look a little "charred", me hearties, so I planned on paintin' t' inside flat black and hoped that would hide t' defects.

Okay, shiver me timbers, so paintin' now comes before actually completin' construction. Before starting, shiver me timbers, I peeled back t' edges o' t' Mylar at t' distal edges o' t' tubes, t' make sure I could find them after paintin' (paintin' t' inside would obscure t' "tails" I had wrapped on t' inside o' t' tube.) T' hard part was FINDING t' edge. Well, blow me down! Many o' t' "tails" that I had thought would provide "handles" had been sandin' off durin' finishing. Ya scallywag! But t' tips that I had wrapped on t' inside (unsealed) part o' t' tubes were still there. Usin' them as guides, I used an Exacto knife t' peel back t' edges o' t' Mylar tape on t' OUTSIDE so I could find it after paintin' t' inside. Arrr! I wrapped newspaper around t' OUTSIDE o' t' tube fins, tapin' it at t' edges/lips. Well, blow me down! Then I used flat black paint t' finish t' INSIDE o' t' tubes. Ahoy! I actually tried rolled up sandpaper t' reduce t' "nap" inside t' tube, arrr, but it didn't work very well. Ya scallywag! Primer would have helped, but I be havin' a struggle justifyin' tryin' t' prime t' INSIDE o' t' engines. Begad! Again, I figured I be goin' for style, me hearties, nay performance, me bucko, me hearties, so I gave up on that part. Avast! I sort o' liked t' internal "charred" look o' t' engines. Avast! As a prior Air Force guy, I noticed t' nozzles o' jet engines on t' flight-line often had blackened look, so I felt I be okay with it for space engines.

Color Scheme: All t' pictures o' t' PLANET Uranus showed it t' be a bluish color, me bucko, arrr, so I figured I'd stay with this.

I primed t' fuselage with Krylon White Primer, shiver me timbers, arrr, three coats, ya bilge rat, with light sandin' betwixt coats. Begad! This filled in t' few defects I had left after t' Filler. Begad! I used Krylon True Blue for t' fuselage - I really like t' color this gave, arrr, and I be happy with t' finish here.

After paintin' t' inside o' t' tube fins black, I took off t' outer maskin' paper. Arrr! Blimey! I then rolled up paper INSIDE t' tubes t' mask t' insides. Ahoy! Blimey! Ahoy! Blimey! This allowed me t' "stack" t' tubes, which actually made paintin' t' outside easier. Blimey! Blimey! Aye aye! Blimey! I had run out o' primer, so I went directly t' paintin' t' outside o' t' tubes Blue Ocean Breeze. I did 3 coats, with a light sandin' betwixt coats. Arrr! Blimey! I liked this color as well. Begad! Blimey! Although I hadn't thought it out ahead o' time, I remember t' three colors that were common for bathroom tiles in t' 60s--- pastel yellow, pastel pink, ya bilge rat, me bucko, and pastel blue. This looked pretty close t' t' pastel blue, me hearties, connectin' t' planetary and Toilet Paper theme.

Moment o' truth, me bucko, what would happen when I peeled off t' Mylar? Actually, I was quite pleased with t' sharp edges. Begad! Avast! Pullin' t' tape off also raised some more "nap" off t' cardboard tubes, exactly what I wanted t' "rough it" for gluing.

As I had expected, ya bilge rat, despite t' masking, thar was a little bleedin' o' black and blue (no pun intended) at t' edges o' t' tube fins. Ya scallywag! I used thin strips o' silver Mylar tape t' cover/accent t' edges here and at t' trailin' end o' t' fuselage. Blimey! As a USAFA grad, t' silver and blue together got me right under t' old squadron patch, matey, as me Dad, ya bilge rat, arrr, a retired AF Navigator/Bombardier says. Begad! I wrapped t' edges o' t' tape into t' inside o' t' tube. Lookin' back, me hearties, this gave t' edge a bit o' a rough look; I probably would just have put it on t' OUTSIDE only, just up t' t' edge.

Now that this was finished, time t' see how things fit together. Blimey! I used medium CA t' glue 4 tubes into two tube-fin pairs, matey, placin' t' glue along one o' t' "naked" strips previously covered by Mylar. Layin' t' tubes flat gave me a good alignment. I then matched up t' remainin' strips on each tube pair with t' strips on each side o' t' tail o' t' fuselage. Aye aye! Ya scallywag! They matched up pretty well, and t' medium CA gave me enough time t' make sure t' alignment was perfect. Avast! Avast, me proud beauty! I got a pretty solid joint (as I later proved in flight, but more on that later.) Fillets weren't needed, and t' fit covered t' "naked" areas.

I pried t' Mylar tape out o' t' defect in t' external coupler. Well, blow me down! Begad! This left a rougher edge.I glued in t' launch lug.If I had t' do it over, arrr, I would have pulled this off AFTER doin' t' filler step, but BEFORE painting, t' get a better look.

Next question, ya bilge rat, ya bilge rat, where t' attach t' shock cord? If I attached it inside, shiver me timbers, it would get hit by t' ejection charge fairly directly, and would also cause problem with slidin' out t' motor pod. Perhaps more importantly, matey, if it came out t' tail, ya bilge rat, t' rocket would fall nose first. Arrr! My launch site is about 3/4 grass, me bucko, 1/4 asphalt. Invariably t' better t' finish on t' rocket, t' more likely it will land on t' asphalt. Blimey! Begad! Also, while t' cardboard/maskin' tape/Elmer's Finish nose cone was holdin' t' finish well, me bucko, I could feel that it was still a little "soft" and didn't think it would hold up t' a hard impact. Arrr! Finally, shiver me timbers, I figured if I could get t' rocket t' descent in a horizontal position, me hearties, arrr, t' rocket body itself would be addin' t' t' drag and slow it down.

With t' rocket painted, shiver me timbers, t' CG o' t' rocket body was right at t' region o' t' external coupler. Ahoy! Well, blow me down! I threaded a needle with me Keelhaul®©™ shock cord into t' tube just above t' coupler next t' t' launch lug, me bucko, and pull about two feet out t' after end o' t' fuselage. Begad! Well, blow me down! I then threaded a needle with t' ENDS o' a long loop o' dental floss through a hole just BELOW t' coupler and out t' aft end o' t' fuselage. Avast! I then threaded ANOTHER loop o' floss (loop 2) through this loop, and pulled loop 2 through t' hole and out t' tail, matey, keepin' t' ENDS o' loop 2 outside fuselage. Ya scallywag! Arrr! I then used loop 2 t' pull t' shock cord BACK into t' tail o' t' fuselage and back through t' hole below t' coupler (there probably is an easier way t' do this, me bucko, but this is what I came up with.) I then tied a tight "loop" o' shock cord, shiver me timbers, runnin' it just next t' t' launch lug, arrr, matey, shiver me timbers, leavin' about 1 1/2 feet o' Keelhaul®©™ loose. Ya scallywag! Yes, me hearties, this loop DID run inside t' rocket body, when t' engine pod would slide in and out, me hearties, but t' cord be runnin' longitudinally and wouldn't obstruct/catch on t' pod. Ya scallywag! I did add a bit o' thin CA t' secure it.

Since I wasn't sure how well me hollow nose cone would hold up t' t' Estes engine ejection blast, shiver me timbers, I cut a bulkhead out o' foam board and place it inside t' body. It slid up t' t' "shoulder" that had been placed on t' front o' t' body tube. Ejection blast would hit t' bulkhead, me bucko, arrr, but nay t' "formed" shape inside o' t' nose cone. Begad! Arrr! Instead o' gluin' it into place, ya bilge rat, I placed a length o' Keelhaul®©™ on this in case I needed t' pull it out later (such as t' add nose weight), and left that loose.

Engine Pod: I originally planned t' use a length o' BT20 as an engine mount AND pod. However, ya bilge rat, matey, after buildin' it, ya bilge rat, me hearties, I discovered I wanted more room for me parachute and streamer. Ya scallywag! I used a BT20 for an engine mount. Well, blow me down! I then wrapped t' end o' a BT5 with electrical tape until it just fit inside t' BT20. Avast! Avast, me proud beauty! T' BT5 acted as BOTH an engine block AND a duct t' direct t' ejection force t' t' front o' t' body, me bucko, shiver me timbers, shiver me timbers, where it hit t' bulkhead. I used foamboard t' cut adapter rings for t' BT20 at t' tail and t' BT5 at t' front o' t' body. Aye aye! Blimey! These were sanded t' slide loosely, but hopefully t' front one would be tight enough t' seal t' ejection charges away from t' chute and streamer. Ahoy! Lookin' back, I probably should have used two adapter rings up front, me bucko, matey, as a little bit o' ejection charge snuck around t' front rin' and slightly charred t' streamer.

I had initially planned on a long white "simulated TP" streamer t' recover t' rocket (in keepin' with t' theme). Arrr! However, me bucko, matey, early on it was clear that given t' weight o' t' rocket a streamer would never safely slow t' rocket AND t' engine pod. Also, again I knew t' nose cone be a little bit "soft" and wanted t' cushion t' landin' o' t' body as much as possible. Aye aye! Begad! My solution had two parts. Ahoy! First, arrr, allow t' engine pod t' completely separate from t' body o' t' rocket, matey, so t' two descend separately. Avast! This reduced t' weight o' t' body o' t' rocket (with t' soft cone). If I needed nose weight, I could add it t' t' front o' t' pod, rather than t' body. This is a NICE trick with aft ejection boost gliders, by t' way. Aye aye! You can adjust your CG by addin' weight t' t' front o' t' ejection pod, matey, matey, without affectin' t' weight or CG o' t' glider itself. Blimey! Then I could use me white streamer t' safely recover t' engine pod (which wasn't really very delicate and was nay that heavy), and a parachute t' recover t' body. Begad! T' shock cord for t' body was attached t' OUTSIDE o' t' fuselage at t' CG, matey, thus t' body descended horizontally under t' chute.

I used two pieces o' white crepe paper t' create t' streamer for t' body tube. Begad! Aye aye! I attached them side by side with silver Mylar tape. Avast! I then accordion folded this into squares t' simulate toilet paper sheets. Arrr! Aye aye! T' silver tape showed on one side, matey, which I thought would be easy t' see (on t' off chance this bird flew outside me launch site-- yeah, arrr, right.) T' other side was straight white, which looked like, well, toilet paper. While for t' real theme this would be "rolled" around t' engine pod "spindle", me experience is that this is unlikely t' "unroll" in flight durin' descent. Ahoy! Blimey! Therefore I stayed with t' accordion fold. Aye aye! Blimey! I used a length 10 times width, me hearties, accordin' t' Stine's book o' optimal streamer length, then added a couple o' inches t' give me space t' attach it t' t' BT5 section o' t' pod.

I used a couple o' thick rubber bands t' link t' parachute t' t' Keelhaul®©™ shock cord attached t' t' mid section o' t' exterior body o' t' rocket.

Note: Originally I used Tim Van Milligan's Model Rocket Design & Construction book t' make two semispherical parachutes, then "ironed" t' two together side t' side. Well, blow me down! T' idea be t' create a parachute with a "cleft" down t' middle, arrr, t' so called "glute chute." (For those who have actually intentionally fallen out o' perfectly good aircraft, shiver me timbers, ya bilge rat, thar be a parachute malfunction called a "Mae West" that looks somewhat similar.) However, while t' parachute looked good, the "glute chute" didn't pack very tightly, me bucko, me hearties, and even reducin' t' engine pod diameter from BT20 t' BT5 didn't give me enough room t' actually use this. Ya scallywag! Begad! I made an 8-line 12-inch chute out o' a green garbage bag (okay, me bucko, was gettin' tired o' t' theme at this point.)

Construction Score: 2

Flight

Moment o' truth arrived. Ahoy! Would this work?

First "gotcha" was t' prep. Begad! T' overhangin' 4 tube fins may (or may not) look cool. Ya scallywag! They do however obstruct access t' t' tail o' t' body. This is bad enough when all you have t' do is stuff an engine in, shiver me timbers, but when you have t' shove in t' entire engine pod with t' accordion streamer AND t' parachute up t' rear, shiver me timbers, those overhangin' tubes REALLY get in t' way.

Anyway, ya bilge rat, shiver me timbers, shiver me timbers, seemed like a C6-3 engine would probably be a good start for this.

Loaded it up on a nearly windless sunny day. Well, blow me down! Ya scallywag! Crossed me fingers. Well, matey, blow me down! Fired. Boost was arced t' t' left (not sure if this was due t' some uneven-ness o' t' fins.) Made it t' roughly 150 feet, arrr, at apogee was travelin' nearly horizontal. Ya scallywag! Ejection was at or near apogee. Begad!

Recovery

Perfect separation o' pod and body. Avast! Streamer extended nicely and at 36 inches long, me bucko, arrr, arrr, 3 inches wide, arrr, white and silver, me hearties, was quite visible. Avast, ya bilge rat, me proud beauty! Chute also opened well. Aye aye! Rocket was far away at this point, but t' descent was either horizontal or slightly tail down (just what I wanted, shiver me timbers, ya bilge rat, t' protect that nose!) Pod and body landed about 100 yards from pad, about 10 yards apart, on t' grass. Ahoy! Begad! Absolutely no damage from t' fall. T' white streamer was very slightly singed.

Had I been smart, ya bilge rat, arrr, I would have counted me blessings and put t' rocket on t' shelf at this point. Aye aye! However, I'm nay smart. Aye aye! I decided t' try it again. Aye aye! On flight two t' engine pod apparently caught on somethin' (may have been packed too tight.) Probably me combined two tubes were nay as smooth internally as a single standard store-bought tube would have been. Aye aye! Negative ejection. Aye aye! Begad! Lawn dart. Nay sure any nose cone would have come thought this unscathed, but me (five coats o' filler, me bucko, multiple hours o' sanding, me hearties, me hearties, multiple coats o' paint - whimper whimper) nose cone accordioned. Nay fixable.

Flight Rating: 4

Summary

Pros:

I had fun, matey, ya bilge rat, probably as much writin' t' background story as buildin' and flyin' t' rocket.
T' paper/maskin' tape/filler nose cone came out well, shiver me timbers, and I think I may use this again for aft ejection models (but will start with a REAL body tube!) Also particularly nice for a large but light nose cone. Blimey! Begad! T' nose finishes well and looks great
Rear Ejection worked well. Well, blow me down! Downsizin' t' central "duct" from BT20 t' BT5 works great and gives you extra space for your recovery device(s). T' BT5 also functions as an engine block. Begad! No waddin' required. Ya scallywag! Avast, me proud beauty! . Begad! Ahoy! Again, arrr, you can use t' long engine pod t' add any needed weight far forward on t' engine pod (and thus anterior on t' rocket in boost phase) to brin' t' CG forward on boost phase without addin' weight t' t' glider at separation.
Separatin' t' pod from t' body allows t' more delicate body t' descend slower.
T' Mylar Mask Strips worked well in allowin' me t' pre-finish and pre-paint parts prior t' assembly, ya bilge rat, but still allow a strong joint. Wonderin' if this might work on an Estes Outlander that I have yet t' build. Suggestions would be welcome.
External shock cord attachment at CG allowed model t' descend horizontally. That a horizontal descent position adds more drag on descent is already well known. Ahoy! However it also allowed me t' avoid t' soft nose hittin' ground, ya bilge rat, which would be t' normal orientation for a rear-ejection model. Avast, me proud beauty! Avast! This technique may be useful in rockets where certain parts o' more fragile than others. Avast! You can adjust t' attachment position t' make it less likely these parts will directly impact t' ground on recovery.
Stayed with Planet Uranus/Toilet Paper Theme
Parts were cheap (until you think o' t' time it takes for extra finishing)
It WORKED! (well, me bucko, at least once.)

Cons:

Paper/Tape/Filler nose cone is slightly soft. Blimey! Arrr! It requires a bulkhead t' protect it from ejection charge and should nay be allowed t' directly hit t' ground on descent (especially nay ballistically.)
External Shock Cord is a bit difficult t' stuff into t' engine pod as you stuff t' engine pod into t' tail o' t' body.
Separatin' pod from body on recovery means you must track both (but t' pod falls pretty fast, ya bilge rat, so shouldn't drift much.)
I couldn't leave well enough alone and stop with one flight.
For some reason t' white paper streamer kept catchin' on me heel.

Overall Rating: 4